Fuse construction



July 1, 1941. H. A. TRIPLETT FUSE CONSTRUCTION Filed Nov. 17, 1959 n we ww m n w a y Patented July 1, 1941 FUSE CONSTRUCTION Hugh A. Triplett, Wilmette, m, assignor to Schweitzer a Conrad, Inc Chicm. 111., a corporation of Delaware Application November 17, 1939, Serial No. 304,903

12 Claims.

This invention relates, generally, to circuit interrupting apparatus and it has particular relation to fuse apparatus.

An object of this invention is to provide for acid, etc. The sections ll of solid arc extinguishing material are held in place by a suitable sleeve IQ of insulating material such as fiber. It will be noted that the rod-like terminal 15 extends holding an arc in a predetermined position with into and substantially fills the bore ll. respect to a moving arcing chamber in a circuit An end member 20 of suitable insulating mainterrupter. terial, such as fiber, is threaded into the upper Another object of this invention is to hold the end of the sleeve I 9 and is provided with a are in the predetermined position, as stated, and suitable aperture through which the rod-like teralso to protect the inner surface of the circuit 10 minal extends. The member 20 is provided with interrupter housing from the heat of the arc. a transverse slot 2| with which a pin 22, ex- A still further object of this invention is to tending transversely through the rod-like terprovide for holding the arc in the predetermined minal l5, interflts to prevent relative rotary moveposition, as stated, and for controlling the movement between the movable arcing chamber l6 ment of the movable arcing chamber conjointly and the rod-like terminal IS. in accordance with two opposing forces, one be- A ring-like clamp nut 23 is threaded onto the ing the force of, the means tending to eifect moveend member and provides a flange against ment of the arcing chamber and the other being which one end of a coil compression spring 24 the reaction force acting in the opposite direccan react. The other end of the spring 24 reacts tion and caused by the arc blowout. 20 against the under side of the flanged head it,

Other objects of this invention will, in part, as illustrated. be obvious, and, in part, appear hereinafter. At its lower end the arcing chamber I6 is pro- This invention, accordingly, is disclosed in the vided with an end member 25, preferably formed embodiment thereof shown in the accompanying of fiber, which is heldin place by a retaining drawing, and it comprises the features of con- 5 member 26 which, in turn, is threaded on to struction, combination of elements and arrangethe lower end of the sleeve IS. The retainer ment of parts which will be exemplified in the member 26 is provided with a shoulder 21 which construction hereinafter set forth, and the scope is arranged to abut a shoulder 28 extending inof the application of which will be indicated in wardly from the lower line terminal l2 for the the appended claims. purpose of limiting the downward movement of For a more complete understanding of the the arcing chamber 16 under the influence of nature and scope of this invention, reference may the compression spring 24, so that it does not be had to the following detailed description taken uncover the lower arcing end of the rod-like terin connection with the accompanying drawing, minal IS. in which: As shown more clearly in Figure 2 of the draw- Figures 1A and 1B constitute a longitudinal ing, the retainer member 26 is provided with sectional view of a. concrete embodiment of the an integrally formed bridge 29 having a suitable invention; and centrally located aperture through which the Figure 2 is a detail sectional view taken along threaded shank 30 of a terminal 3| extends. A the line 2-2 of Figure 1A. nut 32 is threaded on to the shank 30 and securely Referring now particularly to Figures 1A and holds the terminal 3 in a position which is sub- 13 of the drawing, it will be observed that the stantially in axial alignment with the rod-like reference character l0 designates a tubular interminal l5. Strain and fusible elements 33 and sulating housing, preferably formed of glass, 34 are provided for interconnecting the rod-like which has secured to its ends by a suitable alloy terminal [5 and the arcing terminal 3!. It will line terminals II and i2. It will be understood be observed that the lower end 35 of the rod-like that the line terminals H and I2 are arranged terminal I5 is deformed onto the strain and to be mounted in fuse clips. However, it will fusible elements 33 and 34 and that the upper also be understood that provision may be made end 36 of the arcing terminal 3| is likewise deo connecting the terminals H and 12 directly formed onto the other end of these elements. to t e l ne Conducto s- It will be understood that the strain element 33 A cap i3 is threaded on to the upper end of comprises a. relatively high strength wire, such the upper line terminal II and it holds in posias nickel chromium alloy wire, and that the fuse tion thereon a flanged head It from which deshown at 34 is formed preferably of a silver wire. pends a rod-like terminal I5. A terminal 38, having a shank 39 threaded into Movably mounted within the tubular insuthe lower end of the nut 32, has a portion 40 lating housing I0 is an arcing c a ber, S w that is deformed onto a pair of flexible conducgenerally at it, which has a bore l'l formed by tors ll which are long enough to extend out of sections [8 of solid insulating material such as the lower end of the tubular insulating housing .magnesium borate, magnesium hydroxide, boric Ill. The lower ends of the flexible conductors 4| are disposed in suitable slots 42 in the lower end of the lower line terminal I! and are held or clamped in position securely by a flange ll of a clamp nut M, the lower portion ll of which forms a basket or a catching device for receiving the flexible conductors 4| and insuring that they are not expelled beyond the limits shown by the broken lines. The basket or catching device II is provided with suitable apertures II which readily permit the outward flow of the arc blast.

It is desirable that the innersurface of the tubular insulating housing II, which as indicated is preferably formed of glass, be protected from the heat of the are that is formed between the rod-like terminal II and the arcing terminal ii. For this purpose a metallic arc chute or shield 41 is threaded, as shown, onto the lower end of the retainer member and interposes a suitable barrier between the are that is drawn and the inner surface of the tubular insulating housing II. It will be noted that the shield or are chute 41 is relatively short as compared to the distance between the arcing terminal 8i and the lower end of the tubular insulating housing It. Such a construction can be employed since the arcing terminal 3! is securely fastened to the lower end of the movable arcing chamber l6 and is not expellable relative thereto by any pressure that may be generated by the arc blast.

It will be observed that the lower end of the bore i1 and the continuation thereof in the member is flared outwardly to provide a reaction area against which the pressure generated by the arc extinguishing medium that is evolved from the arc extinguishing material can react in a direction which is opposite to the direction in which the arcing chamber I6 is biased by the coil compression spring 24. It is desirable to provide this differential action so that the movement of the arcing chamber It can be ooniointly controlled in accordance with the biasing force of the spring 24 acting in one direction and the force acting on the reaction area provided by the flared-out portion 48 acting in the opposite direction, so that the amount of are extinguishing material that is exposed to the heat of the arc will vary inversely with its magnitude. When such a differential action is not employed and a large quantity of arc extinguishing material is exposed to the heat of a relatively heavy fault current are, a large quantity of arc extinguishing medium is evolved which, in many instances, creates such tremendous pressure that the circuit interrupter is literally blown to pieces. The amount of arc extinguishing medium that is evolved under such circumstances is considerably in excess of that which can be efllciently employed for are extingushing purposes. Since the reaction force of the arc extingushing medium on the reaction area provided by the flared-out portion 48 will vary directly as the magnitude of the arc current, then the movement of the arcing chamber it downwardly under the influence of the coil compression spring 24 will vary inversely with the magnitude of the arc current and, consequently, a relatively small amount of the arc extinguishing material will be subjected to the heat of the are under these circumstances.

It will be obvious that this reaction effect can be varied somewhat by changing the area of the bridge 29 of the retainer member 2. By decreasing this area the effect of the reaction force is increased and vice versa.

Since certain other changes can be made in the above construction and different embodiments of the invention can be made without departing from the scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limitins sense.

What is claimed as new is: 4

1. In a circuit interrupter, in combination, a pair of line terminals in insulated spaced relation, a rod-like terminal extending from one of said line terminals, an arcing chamber biased for movement relative to said rod-like terminal, an arcing terminal fastened to said arcing chamber and movable therewith between which and said rod-like terminal an arc is adapted to be formed. means for releasing said arcing chamber for said movement, stop means limiting movement of said arcing chamber. such that it does not uncover the arcing end of said rod-like terminal, and flexible conductor means interconnecting said arcing terminal and the other line terminal.

2. In a circuit interrupter, in combination, a rod-like terminal, an arcing chamber telescoped with and biased for movement relative to said rod-like terminal, an arcing terminal fastened to said arcing chamber and movable therewith between which and said rod-like terminal an arc is adapted to be formed, means for releasing said arcing chamber for said movement, and stop means limiting movement of said arcing chamber such that it does not uncover the arcing end of said rod-like terminal.

3. In a circuit interrupter, in combination, a tubular arcing chamber having a longitudinal bore, a rod-like terminal fllling said bore, means biasing said arcing chamber for movement along said rod-like terminal, an arcing terminal fastened to said arcing chamber and movable therewith and between which and said rod-like terminal an arc is adapted to be formed substantially axially of the latter, means for releasing said arcing chamber for said movement, and stop means limiting movement of said arcing chamber such that it does not uncover the arcing end of said rod-like terminal.

4. In a circuit interrupter, in combination, a pair of line terminals in insulated spaced relation, a rod-like terminal extending from one of said line terminals, a tubular arcing chamber having its bore formed by material capable of evolving an arc extinguishing medium due to the heat of an arc, said tubular arcing chamber being telescoped with said rod-like terminal from one end and biased for movement with respect thereto and having a reaction area at the other end, an arcing terminal fastened to said arcing chamber and movable therewith between which and said rod-like terminal an arc is adapted to be formed, means for releasing said arcing chamber for said movement which is controlled by two opposing forces, one being the force biasing said arcing chamber for movement along said rodlike terminal and the other being the reaction force of the arc extinguishing medium on said reaction area, and flexible conductor means interconnecting said arcing terminal and the other line terminal.

5. In a circuit interrupter, in combination, a rod-like terminal, a tubular arcing chamber having its bore formed by material capable of evolving an arc extinguishing medium due to the heat of an arc, said tubular arcing chamber being telescoped with said rod-like terminal'from one end and biased for movement with respect thereto and having a reaction area at the other end, and an arcing terminal fastened to said arcing chamber and movable therewith between which and said rod-like terminal an arc is adapted to be formed, means for releasing said arcing chamber for said movement which is controlled by two opposing forces, one being the force biasing said arcing chamber for movement along said rod-like terminal and the other being the reaction force of the arc extinguishing medium on said reaction area.

6. In a circuit interrupter, in combination, a tubular arcing chamber having its bore formed by material capable of evolving an arc extinguishing medium due to the heat of an arc and having a reaction area at one end, a rod-like terminal filling said bore from the other end, means biasing said arcing chamber for movement along said rod-like terminal, and an arcing terminal fastened to said arcing chamber and movable therewith and between which and said rod-like terminal an arc is adapted to be formed substantially axially of the latter, means for releasing said arcing chamber for said movement which is controlled conjointly by the force of said biasing means acting in one direction and the reaction force of the arc extinguishing medium on said reaction area acting in the opposite direction.

7. In a circuit interrupter, in combination, a tubular housing of insulating material having line terminals at its ends, a rod-like terminal extending from one of said line terminals inwardly of said housing, an arcing chamber biased for movement relative to said rod-like terminal, an arcing terminal fastened to said arcing chamber and movable therewith between which and said rod-like terminal an arc is adapted to be formed, means for releasing said arcing chamber for said movement, a shield carried by said arcing chamber on the end thereof toward which it moves for protecting the inner surface of said housing from the heat of the arc, and flexible conductor means interconnecting said arcing terminal and the other line termnial.

8. In acircuit interrupter, in combination, a tubular housing of insulating material havin line terminals at its ends, a rod-like terminal extending from one of said line terminals inwardly of said housing, an arcing chamber biased for movement relative to said rod-like terminal, an arcing terminal fastened to said arcing chamber and movable therewith between which and said rod-like terminal an arc is adapted to be formed, means for releasing said arcing chamber for said movement, a metallic shield carried by said areing chamber for protecting the inner surface of said housing from the heat of the are, said shield being relatively short as compared to the distance between said arcing terminal and the other line terminal, and flexible conductor means interconnecting said arcing terminal and said other line terminal.

9. In a circuit interrupter, in combination, a tubular housing of insulating material having line terminals at its ends, a rod-like terminal extending from one of said line terminals inwardly of said housing, a tubular arcing chamber having its bore formed by material capable of evolving an arc extinguishing medium due to the heat of an are, said tubular arcing chamber being telescoped with said rod-like terminal from one end and biased for movement with respect thereto and having a reaction area at the other end, an

arcing terminal fastened to said arcing chamber and movable therewith between which and said rod-like terminal an arc is adapted tobe formed, means for releasing said arcing chamber for said movement which is controlled by two opposing forces, one being the force biasing said arcing chamber for movement along said rod-like terminal and the other being the reaction force of the arc extinguishing medium on said reaction area, a shield carried by said arcing chamber for protecting the inner surface of said housing from the heat of the arc, and flexible conductor means interconnecting said arcing terminal and the other line terminal.

10. In a circuit interrupter, in combination, a tubular housing of insulating material having line terminals at its ends, a rod-like terminal extending from one of said line terminals inwardly of said housing, a tubular arcing chamber having its bore formed by material capable of evolving an arc extinguishing medium due to the heat of an arc, said tubular arcing chamber being telescope'd with said rod-like terminal from one end and biased for movement with respect thereto and having a reaction area at the other end, an arcing terminal fastened to said arcing chamber and movable therewith and connected thereto by fusible means upon blowing of which an arc is adapted to be formed whereupon said arcing chamber is released for said movement which is controlled by two opposing forces, one being the force biasing said arcing chamber for movement along said rod-like terminal and the other being the reaction force of the arc extinguishing medium on said reaction area, a shield carried by said arcin chamber for protecting the inner surface of said housing from the heat of the arc, and flexible conductor means interconnecting said arcing terminal and the other line terminal.

11. In a circuit interrupter, in combination, a pair of line terminals in insulated spaced relation, a stationary terminal extending from one of said line terminals, an arcing chamber biased for movement relative to said stationary terminal, a movable terminal connected to said stationary terminal by fusible means, flexible conductor means interconnecting said movable terminal and the other line terminal, said arcing chamber being released for movement on blowing of said fusible means, stop means limiting movement of said arcing chamber such that it does not uncover the arcing end of said stationary terminal, and a catching device arranged and adapted to receive said flexible conductor means on blowing of said fusible means.

12. In a circuit interrupter, in combination, a tubular insulating housing, a terminal at each end of said housing, a rod-like terminal fastened to one end terminal and extending into said housing, an arcing chamber telescoping with said rodlike terminal and movable relative thereto toward the other endterminal, a movable terminal connected to said stationary terminal by fusible means, flexible conductor means connecting said movable terminal and said other end terminal, stop means limiting movement of said arcing chamber such that it does not uncover the arcing end of said rod-like terminal, and catching means at the end of said housing where said other end terminal is located for receiving said flexible conductor means when said fusible means blows.

HUGH A. 'I'RIPLETT. 

